1. Field of the Invention
The present invention relates to a connector plug used in an optical connector that connects optical communication cables using single- or multi-core optical fibers.
2. Description of the Prior Art
Optical communication systems have conventionally employed various kinds of optical connectors for connecting optical communication cables. In recent years, an MT (Mechanically Transferable) type connector and an MPO (Multifiber Push-On) type connector capable of being engaged and disengaged simply by a push-pull operation have been proposed as connectors that can easily connect or disconnect optical fiber tapes. These types of connectors all use an MT type ferrule in an optical fiber connecting portion. The optical fiber connectors using the MT type ferrule are constructed so as to be able to easily align the end faces of mating optical fibers by guide pins and are very useful in terms of ease of use, weight and cost.
In recent years, an RJ (Regular Jack) type optical connector has been proposed (for example by U.S. Pat. No. 5,481,634) which incorporates a connector ferrule in an RJ type housing and enables connection and disconnection of optical fibers by an operation similar to the one performed on the electric connector.
The RJ type optical connector applies the connection structure of the electric connector to the optical connector, and its construction is shown in FIG. 17.
The optical connector shown in the figure comprises a pair of RJ type connector plugs 1 (only one of the pair is shown) and an adapter 2. The connector plugs 1 each incorporate a ferrule 4 holding an optical fiber 3 therein. In this optical connector, when the pair of connector plugs 1 are inserted into the adapter 2, end faces of the optical fibers of the opposing connector plugs 1 contact each other, thus connecting the optical fibers 3 of the connector plugs 1.
That is, inserting the connector plugs 1 into the adapter 2 causes an elastic engagement piece 1a provided on one side surface of each connector plug 1 to snap into a recessed portion in the adapter 2, thus holding the connector plug 1 and the adapter 2 in a connected state. The connector plug 1 can be disconnected by pressing a press portion 1c of the elastic engagement piece 1a toward the plug body side while pulling the connector plug from the adapter 2.
With the conventional RJ type optical connector, however, pressing the press portion 1c of the elastic engagement piece 1a easily allows the connector plug to disengage from the adapter 2. Therefore, there is a possibility that the connection may easily be lost as a result of the press portion 1c of the elastic engagement piece 1a contacting external objects. This raises a problem of lack of reliability of the optical connector.
Further, because the elastic engagement piece 1a including the press portion 1c protrudes largely outwardly from the optical connector, cables or the like are likely to get caught by the engagement piece. As described above, inadvertent contact of the elastic engagement piece 1a with other objects will easily result in disconnection.
Another problem is that, when multi-core optical fibers are to be connected by the conventional optical connector, it is difficult to align the positions of the mating optical fibers.
An object of the present invention is to provide a connector plug which can easily be connected to and disconnected from the adapter and at the same time whose connection cannot easily be broken.